According to Drolet (UCLA), Luce (Duke University), and Simonson (Stanford University), it depends.
In an upcoming paper in the Journal of Consumer Research titled "When Does Choice Reveal Preference? Moderators of Heuristic vs. Goal Based Choice" the researchers contend that when our minds are busy with other tasks, our product choices are less likely to reflect our ideal choices. To use some lingo from my new book, they've discovered that our Happy Now "feeling" selves take control of our choices when our Happy Life "thinking" selves become overwhelmed with . . . well . . . thinking.
Their research also identified two basic factors that determine our use of heuristics (or mental shortcuts, rules of thumb, brand names, etc.). One is our relative desire to think through our choices (referred to as NFC, or need for cognition), and the other is our cognitive load (how busy we are thinking about things).
So what does all of this tell us? Nothing new, really. But it is a good reminder nonetheless: If you want to make appropriate choices for long-term satisfaction, slow down and make a considered choice. But here's the bad news: When we become overwhelmed with the sheer amount of choice and information (cognitive load), we're going to have the tendency to rely on heuristics (mental shortcuts, rules of thumb, brands, etc.) in any event.
I particularly liked this paradoxical statement by the authors: "The present research provides new insights into the conditions under which consumers' choices will be reflective of their self-goals and hence the degree to which choices might be expected to reveal preferences."
Which "self's goals?" I believe it should read, " . . . the degree to which choices might be expected to reveal Happy Life's preferences." I'm pretty sure that Happy Now's goals were optimized. :)